1. Field of the Invention
The invention is directed to a power semiconductor module and more particularly to a compact pressure-contact-connected power semiconductor module without a base plate and having a frame-like insulating housing, with at least one substrate and a pressure device.
2. Description of the Related Art
Known power semiconductor modules as shown, for example, in German Patent No. DE 197 19 703 A1. According to the prior art, such power semiconductor modules comprise a housing having at least one electrically insulating substrate which is arranged in the housing and is preferably intended to be directly mounted on a cooling component. The substrate, for its part, comprises a body made of an insulating material having a plurality of structured metal connecting tracks, which are situated thereon and are insulated from one another, and having power semiconductor components which are situated on the tracks and are connected to these connecting tracks in a circuit-compliant manner. Furthermore, known power semiconductor modules have connection elements for external load and auxiliary connections as well as connecting elements which are arranged in the interior thereof.
Other known pressure-contact-connected power semiconductor modules, are disclosed in German Patent Nos. DE 199 03 875 A1 and DE 101 27 947 C1.
The module disclosed in German Patent No. 199 03 875 A1 has a pressure device comprising a stable pressure element for introducing pressure. The element has an advantageous ratio of weight and stability and, for this purpose, is in the form of a shaped plastic body with an internal metal core and also has electrically insulating bushings.
Furthermore, the pressure device has an elastic cushion element for storing pressure and a bridge element for introducing pressure into separate regions of the substrate surface. In this case, the elastic cushion element is used to maintain constant pressure conditions under different thermal loads and over the entire life cycle of the power semiconductor module. The bridge element is preferably in the form of a shaped plastic body having an area which faces the cushion element and from which a multiplicity of pressure fingers extend towards the substrate surface. Such a pressure device is preferably used to urge the substrate onto a cooling component and hence to reliably produce permanent heat transfer between the substrate and the cooling component.
German Patent No. DE 101 27 947 C1 discloses a further power semiconductor module, the load connection elements of which are designed so that sections of them run very close to one another at right angles to the substrate surface and have internal contacts which extend therefrom, make electrical contact with the conductor tracks and simultaneously exert pressure on the substrate. Thus they preferably establish thermal contact between the substrate and a cooling component. In this case, the pressure is introduced, by way of example, using the above-mentioned means according to the prior art.
The disadvantage of power semiconductor modules which are formed in this manner without a base plate is that, during the pressure-introducing contact-connection of the internal contact devices to the conductor tracks of the substrate, the electrically insulating substrate may rotate with respect to the frame-like housing in the mounting process as a result of the lack of a base plate. The force caused by rotating the substrate with respect to the housing may damage the substrate during mounting and thus cause a loss of performance, including the possible destruction of the power semiconductor module.
Another disadvantage of such power semiconductor modules having spring contact elements as the load and auxiliary connection elements is that the internal contacts of these spring contact elements may laterally slide off the structured conductor track as a result of the introduction of pressure and give rise to a loss of contact which may result in reduced performance of the power semiconductor module and, in the extreme case, to the total failure of the module.